My 1985 2.3 8V starts slowly (like low battery) and seems to have less battery charge after running for a while. Battery is new. When the car is running at 1100 rpm, voltage at battery terminals is 12.84. If I rev to 3000 or so it jumps to 13.25 or there abouts. I replaced the regulator a couple months ago and have 3 hours of running time on the car since then. I think I need a NEW alternater. Am I thinking correctly?